The present invention relates to a seat belt tightener having an electrical tightening drive.
DE 195 20 721 A1 teaches a vehicle occupant restraint device with an information system, for instance a pre-crash sensor, used to anticipate a crash prior to any deformation occurring to the motor vehicle and to emit a corresponding signal. This should result in pulling forces passing into a seat belt by an electromotive tightening drive prior to the actual crash. The length of the seat belt extracted can be measured by a sensor to generate an optimal pulling force for tightening the seat belt. This enables the vehicle occupant to already be placed in an optimal position preceding an actual crash, for instance during emergency braking. The known vehicle occupant restraint system evaluates signals that are detected by pre-crash sensors immediately before a crash.
EP 0893313 A2 teaches a vehicle occupant restraint device with a seat belt which, with the help of an electromotive drive, can carry out various optional functions, such as reducing the force of the motive spring when a belt is fastened, adjusting the belt force limitation and the seat belt tightening.
It is known from DE 195 15 055 A1 that, to control the driving stability of a motor vehicle, a set value for a controlled variable, in particular the yaw angle speed, is determined from a motor vehicle model imitating motor vehicle characteristics, and the motor vehicle model is modified in relation to the driving speed.
In the present invention has an array of sensors used to detect specific vehicle dynamic conditions and the respective sensors generate indicating signals that are proportional to the detected condition and the signals are transmitted to an evaluating device. From the received signals, the evaluating device can detect a potential crash situation and, above a determined vehicle speed threshold, for instance 30 km/hour, the evaluating device controls the electrical seat belt tightening drive, if a potential crash situation was detected from the electrical indicating signals.
It is preferred that indicating signals consist of signals that reflect the operating performance of a motor vehicle. Such indicating signals are traditionally used for the control of vehicle stability (DE 195 15 055 A1).